This invention relates to semiconductor lasers and more specifically it relates to an integration of a diode laser with a traveling-wave semiconductor optical amplifier wherein the amplifier has a gain profile spatially shaped to improve output beam control and it incorporates an integrated lens at its output.
Conventional semiconductor lasers emit coherent radiation having particularized transverse electric (TE) modal characteristics. For many applications, the emitted coherent radiation is unsatisfactory because it does not offer sufficient power to meet minimum requirements. Typically, a mode designated as TE.sub.0,0 provides greatest power and has other desirable attributes, therefore operation of semiconductor lasers to emit radiation having this fundamental mode is desirable. Increasing the power output of a semiconductor laser by more energetic pumping often results in an addition of unwanted higher order modes to the output beam of the laser. These unwanted modes limit the effectiveness of increasing output power in this fashion.
In response to a desire for greater power in the fundamental mode, semiconductor laser designers provide amplifiers coupled to the semiconductor laser output which boost the effective power output from the semiconductor laser. These amplifiers while effectively boosting output power, are not optimally efficient because of coupling losses. These amplifiers can also distort the fundamental mode output from the laser if any modal mismatch exists at the entrance to or in the gain of the amplifier section. Contributing to a difficulty of providing suitable amplifiers is a severity of the divergence of the laser beam.